My client's design policy is to create Z-copies of the SAP standard settings. We did so when setting up PO outout control, e.g. created a Z-copy of message schema RMBEF1 and assigned that to Purchase Order (Usage; "U" and Appl: "EF").

However, now when we are to implement ERS I cannot find a way to assign the newly created message schemas to for example transction MRRL and MRKO. The SAP standard ones must some how be "assigned" to the different transactons in LIV.